1. Field of the Invention
The present invention relates to a recording media control apparatus, a recording media controlling method, and a computer program. More particularly, the invention relates to a recording media control apparatus, a recording media controlling method, and a computer program for controlling the performance of recording media such as hard disks that can be randomly accessed by a read/write head doing seeks on their recording surface.
2. Description of the Related Art
Furthermore, the present invention relates to a recording media control apparatus, a recording media controlling method, and a computer program for protecting recording media from the environment of high and low temperatures by controlling the operations of recording and reproduction to and from the media in keeping with changes in the temperature environment. More specifically, the invention relates to a recording media control apparatus, a recording media controlling method, and a computer program for controlling the recording and reproduction to and from recording media in conformance with the temperature environment through the use of a temperature sensor built in a recording media unit.
Along with the development of information technology covering information processing and data communication has emerged the need to reuse information created or edited in the past. This trend has lent growing importance to information storage technology. To date, information recording devices utilizing diverse media such as magnetic tapes and magnetic disks have been developed and popularized. Of these, disk-type recording media such as hard disks basically permit random access by a read/write head doing seeks in the radial direction over the recording surface of a rotating disk.
Hard disks have already gained widespread acceptance. For example, the hard disk is employed in standard local recording devices for use with personal computers, the hard disk accommodating an operating system (OS), applications and other diverse software which have been installed with a view to starting up and operating the computer, as well as various data files that have been created or edited.
Information apparatuses handling large amounts of data such as digital video cameras have come to utilize hard disks as local recording devices or externally connected recording devices (e.g., see Japanese Patent Laid-open Nos. Hei 8-140027 and Hei 9-168109). The hard disk, when used in the recording device for the digital video camera, permits digital recording of the data constituting numerous high-quality pictures and allows random access to the data recorded thereon. Also, the hard disk-equipped digital video camera may be connected to a computer for the handling of files and the editing of pictures on the latter. Recently, hard disk drives have been incorporated in devices designed primarily for portable use such as in portable music players, as well as in devices mounted on mobile units such as navigation devices. Using the hard disk in any of these information apparatuses translates into lower weight, smaller volume, and less manufacturing cost of the apparatus in question than if removable magnetic tapes or optical disks were utilized. In addition, not limited by the size of the recording media or by the layout of mounting arrangements, the apparatus can be reduced in size and thereby offers a higher degree of flexibility in design.
The hard disk drive utilizes techniques for creating an air space between a magnetic head and a magnetic disk by rotating the disk, thereby floating the magnetic head slightly over the disk coated or vapor-deposited with a magnetic substance. That is, while the magnetic disk is at rest, the magnetic head remains lightly in contact with the magnetic disk surface. As the magnetic disk is rotated, the resulting air flow causes the magnetic head to float over the disk surface for write or read operations. The magnetic disk and the magnetic head stay close to yet detached from each other, whereby high-density magnetic recording is implemented.
The above-mentioned mechanism turns the hard disk drive into a recording apparatus vulnerable to shock. Various arrangements are thus needed to avoid physical contact between the magnetic disk and the magnetic head. For example, one known arrangement involves using an acceleration sensor to detect a fall of the apparatus incorporating the hard disk drive. Before an imminent impact of the apparatus on the ground, the magnetic head is retracted so as to protect the hard disk.
In an environment where the internal temperature of the apparatus is extremely low, getting the disk to start up and rotate can generate abnormal sound in a resonance mode different from what is in effect at room temperature. Or it is feared that at the time of contact (CSS: contact start stop) between the recording surface of the disk and the magnetic head, an increasing viscosity of a lubricant in use will give rise to an increase in abrasion resistance. For these reasons, the countermeasures above against shock need to be supplemented by arrangements for protecting the hard disk from high and low temperatures while recording and reproduction to and from the disk are being controlled. In particular, portable devices such as digital video cameras employing an internal hard disk are expected to be used frequently outdoors or in an environment of severe temperature characteristics such as cold regions. This further increases the need for controlling disk access operations in keeping with the temperature being detected.
Illustratively, a recording and reproducing apparatus and a method for controlling it have been proposed whereby the internal temperature of an incorporated disk drive is detected so that if the detected temperature is below a predetermined level, the disk drive is inhibited from accessing its disk-like recording media (e.g., see Japanese Patent Laid-open No. Hei 10-340521). The operation of the disk drive is thus suppressed at low temperatures to avoid its damage or destruction, and the temperature of the disk drive is raised quickly to room temperature to ensure reliable performance. The proposed apparatus and method envisage guaranteeing the performance of the hard disk drive within a predetermined temperature range.
In order to implement the control of recording and reproduction in keeping with the temperature environment, it is preferred to measure the temperature of the hard disk drive as accurately as possible. The reason is that a failure to detect the state where the temperature is low enough to trigger the suppression of access operations can lead to malfunction or a device fault, and that a failure to detect the state where the temperature is high enough to warrant the resumption of access operations can bring about reduced service because of unnecessarily inhibited access.
There are two major methods for measuring the temperature of the hard disk drive: by using a temperature sensor attached externally to the drive unit, or by resorting to a temperature sensor placed inside the drive unit. Needless to say, the second method permits more accurate measurement of the temperature.
With regard to the second method above, a disk drive has been proposed which incorporates a temperature sensor and which is instructed to start and stop depending on the change detected by the sensor in the internal temperature (e.g., see Japanese Patent Laid-open No. 2007-179662). Also proposed is an information processing apparatus which incorporates a plurality of hard disk drives and which has a temperature sensor installed close to a seek motor inside the preferentially utilized drive unit (e.g., see Japanese Patent Laid-open No. 2008-59652). Another proposal involves an information processing apparatus which uses both a temperature sensor attached externally to a hard disk unit and a temperature sensor incorporated inside the unit so as to protect the hard disk from high and low temperatures (e.g., see Japanese Patent Application No. 2007-194443 having been assigned to this applicant).
As mentioned above, the acceleration sensor has been used to protect the disk from shock. Some of the currently available acceleration sensors incorporate temperature sensors. (For example, Japanese Patent Laid-open No. 2004-24551 proposes a semiconductor device wherein sensors including a temperature sensor, an acceleration sensor, and red light/infrared light sensors are formed on a single semiconductor substrate.)
The inventors are of the opinion that the setup having the temperature sensor incorporated in the drive unit is preferable for two reasons: because an acceleration sensor with no temperature sensor placed inside is inexpensive, and because the temperature sensor inside the drive unit permits more accurate temperature measurement.
Also, the inventors believe that the measures to protect recording media against temperatures should preferably be taken in keeping with the performance status of the host incorporating the hard disk drive, in such a manner as not to hamper normal operations including the writing and reading of data to and from the disk which are carried out by the host.
The control over detection and monitoring of temperatures in the hard disk may be performed primarily by one of two methods: by the host, or by the drive unit on an autonomous basis. According to the first method, the host may issue a temperature acquisition request command to the hard disk and, given a return value therefrom, may control the detection and monitoring of temperatures accordingly. The second method is not very practical for common apparatuses utilizing hard disk drives because of the need to implement additional arrangements whereby the host would notify the hard disk drive of its own performance status.
Even with the first method above, an inordinately short cycle in which the host requests temperature acquisition can lead to excess overhead in the process of reading and writing data and, it is feared, to reduced performance. Conversely, an excessively long cycle in which the host requests temperature acquisition can make it impossible to control recording and reproduction quickly enough in keeping with temperature changes for protection against temperature fluctuations. That in turn makes it impossible to prevent a hard disk error or destruction.